changes in the DNA of the cell to promote cancerous
behaviors. One of the most exciting recent discoveries is that
some epigenetic abnormalities may be reversible.

Cancer Development:
Influences Outside the Cell

It is clear that cancer develops as a result of alterations tothe genetic material of a cell that lead to malfunctions in itsbehavior. Research has revealed, however, that interactionsbetween cancer cells and their environment—known asthe tumor microenvironment—as well as interactions withsystemic factors, are an important part of cancer development(see sidebar on Cancer Growth: Local and Global Influences,p. 12). ;is means that cancer is much more complex thanan isolated mass of proliferating cancer cells. ;erefore, if weare to advance our mission to prevent and cure all cancers,we must develop a more comprehensive, whole-patientunderstanding of cancer.